A Colormetric and Fluorescence Probe for Highly Specific Cu²⁺ and its Application in Live Cell Imaging

Fluorescent probes are intriguing material for ion detection. In this study, 4,4-difluoro-4-bora3a,4a-diaza-s-indacene (BODIPY) containing a dipicolylethylenediamine unit was developed as a colorimetric and fluorescence "turn-off" probe for Cu²⁺. The probe exhibited higher selectivity for Cu²⁺ than other common metal ions with a detection limit of 8.49 μM. With increasing Cu²⁺ concentration, the probe showed a red-shift in the absorption spectrum as well as fluorescence quenching, possibly due to the intramolecular charge transfer effect of the probe-Cu(II) complex. Furthermore, the probe was used for imaging Cu²⁺ in living cells based on confocal fluorescence imaging. The results show that the probe is an effective tool for detection copper ions.